To prevent improper copying of documents, it is known for an image processing system to detect a specific original and prohibit copying based on that detection. An example of such an image processing system is disclosed in U.S. Pat. No. 5,832,112 to Funada et al. The Funada et al. system judges whether input color image information is a predetermined image, and prohibits copying depending on the judgment. This judgment is always performed on a document being copied, which can waste system resources where certain documents or copy processes are not capable of producing counterfeits.
The Funada et al. system, like other conventional color image processing systems, includes a 3-line CCD sensor for detecting colors in an original image. The 3-line sensor generates color information for red, green and blue (RGB) data. Typically, the RGB data is converted or translated into cyan, magenta and yellow (CMY) data. Neither the RGB data nor the CMY data identifies any black data in the original image. To identify the black data, another translation is performed on the CMY data to obtain CMY and black (K) data. Systems like that of Funada et al. have been designed and configured to process images based on the generated RGB data. They have not, however, been designed or configured to process images based on a 4-line CCD sensor generating both RGB data and K data.
One parameter involved in image processing is increasing or decreasing a zoom level of the document being copied. To increase or decrease the zoom level in the reproduced document, adjustment is made both in the main scanning direction, i.e., the direction in which the carriage scanner travels, and the sub-scanning direction, i.e., the direction perpendicular to the main scanning direction. The carriage scanner is the element that moves a lamp to illuminate the document being copied. In conventional systems, the adjustment in the main scanning direction is done by adjusting the speed of the scanner carriage, and the adjustment in the sub-scanning direction is effected through image processing algorithms.
In some image processing systems, the zoom level can vary significantly from the regular zoom level of 100%. The range can be from, for example, a low zoom level of 50%, to a high zoom level of 200%. With steps of 1% between each zoom level, the scanner carriage must be capable of a significant number of speed adjustments. This significant number of speed adjustments greatly raises the cost for motor control of the scanner carriage, and makes them complicated. It would therefore be desirable to have a zoom level adjustment system that reduces the cost and complexity of the motor control of the scanner carriage.